* migrate attestation pool tests from get_crosslink_committees_at_slot(...) to get_crosslink_committee(...)
* rm obsolete, unused get_crosslink_committees_at_slot_cached(...) and migrate tests/test_state_transition from get_crosslink_committees_at_slot(...) to get_crosslink_committee(...)
* migrate tests/testutil from get_crosslink_committees_at_slot(...) to get_crosslink_committee(...)
* use more pervasive caching infrastructure, initially of compute_committee; remove buggy (and per-index) shuffling to fix research/state_sim, which was noticing validators on multiple shard committees; rm now-unused specific get_attesting_balance_cached
* add some get_active_validator_index caching
* rm obsolete/unused get_attesting_indices_cached
* rm get_crosslink_committees_at_slot(...)
* some more 0.7 changes -- some of which can't be completed pending some data structure updates -- and shard handling changes to offset with epoch start shards
* Initial move constants to mainnet preset
* Bump fixtures to include shuffling with minimal preset
* Add minimal preset with shuffling test
* Add minimal preset to the full test suite
* use preset() everywhere
* signed_root -> signing_root
* implement new process_deposit; update timing parameters to 0.6.1; update Deposit to 0.6.1 and remove DepositInput
* update get_active_validator_indices and get_epoch_committee_count to 0.6.1; rm get_current_epoch_committee_count, get_previous_epoch_committee_count, and get_next_epoch_committee_count; bump state_sim default validator count a bit more
* re-introduce 0.5.1-ish get_active_validator_indices, get_epoch_committee_count as scaffolding for still-0.5.1ish shuffling
* no need to pass prev_block_root when updating state
* some Slot fixes
* fix `hash_tree_root` for Slot, Epoch
* detect missing hash_tree_root type support
* remove some <0.5 state checks
* ssz: update to 0.5.1:ish
* slightly fewer seq allocations
* still a lot of potential for optimization
* fixes#174
* ssz: avoid reallocating leaves (logN merkle impl)
* rm gone-in-0.5.0 Proposal, verifyBlockSignature, and slot check which moved to spec function processBlockHeader
* mark get_attestation_participants and get_epoch_committee_count as 0.5.1; finish updating processAttestations to 0.5.1; add kludgy workaround for bug relating to get_winning_roots_etc using crosslink_data_root as index when we have that as ZERO_HASH for all leading to it confusing attesters on different shards; rm BeaconState.latest_attestations, which splits into previous_epoch_attestations and current_epoch_attestations
* Fix CI due to removed latest_attestations field
* fix state db lookup typo
* fix randao reveal slot when proposing blocks
* only store blocks that can be applied to a state
* store state at every epoch boundary (yes, needs pruning!)
* split out state advancement function when there's no block
* default state sim to 0.9 attestation ratio
* convert some asserts to doAsserts to keep them in release mode builds; rename get_initial_beacon_state to get_genesis_beacon_state to track spec; switch target spec version to 0.3.0; switch references to penalize_validator to slash_validator/slashValidator to track spec; make some function returns safer by omitting 'return'
* 2x shuffling speedup by hoisting pivot calculations per https://github.com/protolambda/eth2-shuffle
* fix initial attestation pool on reordered attestations
* simplify db layer api
* load head block from database on startup, then load state
* significantly changes database format
* move subscriptions to separate proc's
* implement block replay from historical state
* avoid rescheduling epoch actions on block receipt (why?)
* make sure genesis block is created and used
* relax initial state sim parameters a bit
* spec updates
* balances move out to separate seq
* bunch of placeholders for proof-of-custody / phase1
* fix inclusion distance adjustment
* modify state in-place in `updateState` (tests spent over 80% time
copying state! now it's down to 25-50)
* document several conditions and conversations
* some renames here and there to follow spec
* spec updates
* random small updates
* ssz no longer sorts by field, fix enum serialization
* rewire block processing a little to avoid a few state copies
* add a state simulation tool that writes out jsons
* use repeat_hash from spec in randao
* add some logging to state processing
* export crypto string converters in spec insulation layer
* enable block signature verification
* ssz: add support for arrays, remove custom data type code
* correctly handle previous and new block
* add trivial block processing tests
* prefer iterative repeat_hash
* state transition mostly done
* handle most specials and slashings